This invention relates to the field of undercutters. Undercutters are used to scoop out contaminated gravel from beneath railroad tracks. These devices employ a chain mechanism pulled by drives means around an elongated bar in a manner similar to that of a chain saw. An undercutter however utilizes a much larger chain and cutting mechanism, and exists in an extremely abrasive environment. Thus, by its nature the chain is extremely heavy, several hundred pounds, requiring two or more men to lift and remove it to gain access to the bar for replacement, and difficult to do in the field without lifting equipment. In particular, after a certain number of hours, certain parts of the bar wear out and need replacing, requiring the machine be shut down for time consuming, burdensome and difficult removal of the chain so as to allow access to the bar for replacement or maintenance of parts. Regardless of whether it's an off the track undercutter or on track undercutter, the chain has to be loosened, removed or disassembled.
It is therefore desirable to have easily replaceable parts. The removal of the chain is a significant requirement in the prior art and results in considerable down time when the machine is out of commission. If replacement parts were such that removal of the chain were unnecessary, then considerable time, expense, labor and likelihood of injury is significantly reduced, resulting in more work time available for the machine as well. It is estimated that given the device often requires maintenance every several hundred hours that thousands of dollars can be saved if the chain need not be removed during this type of maintenance. Moreover, the chain tends to wear parts of the bar more in some areas than others. For example, the cutting face of the bar (facing the material being cut into) tends to wear faster because of the additional pressure on the chain and bar at the cutting face side.
Prior art discloses a removable C-channel segment within which the chain rides and is guided, however replacement of these worn parts requires actual removal of the chain; moreover, the entire C-channel is primarily unusable and needs replaced. The invention provides part that, because only portions are worn, can continue to be used by reversing, rotating, flipping and/or interchanging. While this alone is important, the ability to do so without removing or loosening the chain is significant. It also allows for targeted maintenance, to relatively quickly change a discreet particularly over worn section. In other words, if one has to remove the chain, with the difficulties described above, one may as well replace more, if not all, parts while doing so. This is not the case with the invention, as only those fully worn parts need be replaced or changed.
The invention comprises a set of bolted on pieces on top and on the bottom in a manner that provides the chain guide channel while maintaining structural strength, that allows for easy targeted removal, by removing the bar top and bottom while the chain remains essentially in place. The bar need not be replaced, nor is it necessary to remove, or even loosen, the chain. Moreover, the parts most worn, for example those on the cutting face side, can still be used by flipping them, reversing them, rotating them, or interchanging them to the backside or elsewhere, to utilize unworn portions of the segment. These parts, smaller and less expensive from the start, can now have double the life span compared to those in the prior art. Still further, these parts typically get fully worn before discarding. Furthermore, the bar parts are expensive and heavy (up to a hundred pounds each) and the planar nature lends the parts to be refurbished and recycled by grinding down and recoating.
It is therefore an object of the invention to create an undercutter device that allows for easy maintenance of the bar and parts related to it without removing the chain, and to allow reusing interchangeable parts. It is also an object to provide an easily maintained bar structure for the undercutter that is safer to maintain and minimizes the possibility of injury that is inherent when removing a several hundred pound chain that also allows for less downtime of the machine during maintenance and thus more profitable use of the machine. Other features and objects will be apparent from the disclosure herein.